1. Field of the Invention
The present invention relates to a device and a method for operating a discharge lamp. The invention also relates to a light source device and a display that include the discharge lamp operating device.
2. Description of the Related Art
Liquid crystal displays that employ a liquid crystal panel as a display unit are widely prevalent. As is well known, the liquid crystal panels are not self-luminous devices. Therefore, the liquid crystal panels allow the passage therethrough of light emitted from a light source device referred to as a so-called backlight, and modulate the passing light based on video signals to thereby display images.
Currently, discharge lamps such as cold cathode fluorescent lamps are widely used as a light source of the liquid crystal display. Such discharge lamps have advantages of a long life, no necessity for heating for operation thereof, etc.
In general, such discharge lamps are operated by application of AC voltage thereto. For application of AC voltage to a discharge lamp, an inverter is used. The inverter converts a DC supply voltage to an AC supply voltage. Applying a voltage as the AC supply voltage to a discharge lamp allows the operation of the discharge lamp. A related-art example is disclosed in e.g. Japanese Patent Laid-Open No. Hei 10-335084.
It is known that when a discharge lamp is operated through AC driving, leakage current from the discharge lamp arises. The occurrence of leakage current during the operation of the discharge lamp correspondingly reduces the amount of current flowing through the discharge lamp. This current reduction possibly causes e.g. a decrease in the luminance and an increase in reactive power during the operation of the discharge lamp. Therefore, it is preferable that leakage current during the operation of a discharge lamp be reduced as far as possible.